Effects of Overexpression of ET-1 in Mammary Gland Physiology

Abstract

Amaç: Endotelin (ET-1), kardiyovasküler sistemde güçlü bir vazo-konstrüktör rolü olmasının yanı sıra birçok fizyolojik olayda kendini göstermektedir. ET-1 ekspresyonunun özellikle gebelik ve emzirme döneminde ortaya çıkması nedeniyle hem emzirme hem de yeni doğan için önemli bir işlevi olduğu düşünülmektedir. Bu çalışmada ET-1 transgenik fare modeli kullanarak meme bezi üstünde ET-1'in etkilerinin incelenmesi amaçlanmıştır.

Gereç ve Yöntem: Meme dokusunun farklı fizyolojik durumlarında (ergenlik, gebelik, laktasyon ve involusyon) ET-1 in etkisini incelemek üzere karşılaştırmalı bir çalışma gerçekleştirildi. Meme dokularından paralel kesitler hazırlanıp hematoksilen-eozin (HE) boyama ile mik-roskobik inceleme yapıldı. Meme bezi gelişimi ve metabolizmasın-da önemli görevleri olan sinyal proteinlerinin (STAT5, AKT, STAT3) analizlerinde Western blot tekniği kullanıldı. Metabolik faaliyetlerde anahtar rolü olduğu bilinen genler (WAP, beta kazein, GLUT-1, SRBF-1 Claudin 8, IL-6, LIF) gercek zamanlı polimeraz zincir reaksiyonu (RT-PCR) tekniği ile analiz edildi.

Bulgular: ET-1 transgenik farelerde sırasıyla sekresyonel hasar, laktasyonel yetmezlik ve erken involusyon gibi patolojik bulgular tespit edildi. Transgenik grupta STAT5’in aktivasyonunun bu durumdan etkilenmediği ancak AKT protein seviyesinde düşüş oldu-ğu saptandı. İnvolusyonda görülen STAT3 aktivasyonu transgenik farelerde laktasyonun 3. gününde tespit edildi. Ayrıca, RT-PCR analizleri ile transgenik farelerde yüksek ET-1 ifadesine bağlı ola-rak WAP'ın baskılandığını LIF protein ifadesinin belirgin bir şekilde arttığı tespit edildi.

Sonuç: Sadece gebelik ve laktasyon döneminde ifade edilen ET-1'in laktasyon ve yeni doğan için önemli bir işlevi olduğu düşünül-mektedir. Yüksek ET-1 ifadesi meme fizyolojisinde önemli olduğu bilinen genlerin sentezini doğrudan etkileyerek laktasyonel yeter-sizliğe sebep olmuştur. Bu çalışmada ET-1 regülasyonunun meme bezi gelişiminde ve süt sekresyonu fonksiyonunda kritik bir rol oynadığı gosterilmiştir.

Keywords

• Endothelin
• lactational incompetence
• WAP
• LIF
• preco-cious involution
• transgenic mice

Effects of Overexpression of ET-1 in Mammary Gland Physiology

Abstract

Objective: Alongside its role as a potent vasoconstrictor in the cardio-vascular system, endothelin-1 (ET-1) is involved in numerous physio-logical processes. Its expression is thought to be an important function for both breastfeeding and newborns since it occurs especially during pregnancy and lactation. In this study, we projected the effects of ET-1 on mammary gland physiology employing ET-1 transgenic mice.

Material and Method: In this study, we compared the mammary glands of ET-1 transgenic mice with the control mice in different physiological states (adolescence, pregnant, lactation and involution). Parallel sections were prepared from mammary glands and microscopic examinations were performed with hematoxylin and eosin (HE)-staining. Western blot techniques were used in the analysis of signal proteins that have important functions in mam-mary gland development and the metabolism (STAT5, AKT, STAT3). Genes known to play a key function in metabolic activities (WAP, beta casein, GLUT-1, SRBF-1 Claudin 8, IL-6, LIF) were analyzed em-ploying real-time PCR techniques.

Results: It was determined that ET-1 transgenic mice developed pathological conditions such as secretory damage, lactational failure and early involution, respectively. Our Western blot studies showed that STAT5 activation was not affected by this process in the trans-genic group, but a decrease in AKT protein level was detected. We detected STAT3 activation seen in the involution process in trans-genic mice only on the 3rd day of lactation. In addition, we found that WAP was suppressed due to high ET-1 expression and that LIF protein expression increased significantly, by real-time PCR analysis.

Conclusion: ET-1 expression is thought to be an important func-tion for both lactation and newborns, especially during pregnancy and lactation. In this study, it was found that when ET-1 expression increases, it causes lactation failure in the mammary gland and directly affects the synthesis of genes known to be important in mammary physiology. Hereby, it was determined that the regulation of ET-1 plays a critical role in the development and secretory function of the mammary gland.

Keywords

• Endothelin
• Lactational incompetence
• WAP
• LIF
• Precoicious involution
• Transgenic mice

Supporting Institution

Charite Universitätsmedizin Berlin

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